170/ crank= 225 crank shaft

The 170 had a shorter stroke than the 225, but the same head and valves. Low end torque was less, but ultimate power was the same. In addition, with the lower block height it was a sturdier engine, and with the shorter stroke could rev higher with less chance of an rpm failure.

as far as the crank swap memike, im no /6 wiz , i wouldnt want to answer that without being 100% positive, so i will leave that to the experts...